Two-cycle internal combustion engine



Sept. 18, 1934. THQMANN 1,973,859

TWO-CYCLE INTERNAL COMBUSTION ENGINE Filed Ju ne 2. 1932 Patented Sept.18, 1934 UNITED STATES TWO-CYCLE INTERNAL COMBUSTION ENGINE RobertThomann, Winterthur, Switzerland, as-

signor to the firm of Sulzer Freres Societe Anonyme, Winterthur,Switzerland Application June 2, i932, Serial No. 614.867

InS

witzerland April 29, 1932 Claims. (01. 123-65) Two-cycle internalcombustion engines are known in which subdivided ports are provided forthe introduction of air, the upper ports being uncovered by the pistonbefore it covers the exhaust ports, and in which air at a lower pressureis led in through both rows of portsand also air at a higher pressurethrough the upper row of ports into the working space of the cylinder.

Such internal combustion engines, in which the air can flow into theworking cylinder in three different ways, possess the drawback that thescavenging air can flow out too soon through the exhaust ports. Theinvention relates to a two-cycle internal combustion engine with theinlet ports arranged opposite the exhaust ports,

with automatic members for scavenging the cyl-.

inder through air at a low pressure, and positively'operated members forcharging and. supercharging the cylinder with air at a higher pressure,and consists in making the scavenging start suddenly and through a wideopening by merging the preexistent plurality of small ports into onesingle large row, so that practically the whole of the space possible tobe used for inlet purposes is thereby used for the flow of scavenginair, which is also positively guided towards the cylinder cover, wherebythe'exhaust gases are positively and completely pushed directly out ofthe exhaust ports, That is to say common inlet ports, closed by thepiston during the compression stroke after the exhaust ports, areprovided to effectuate both the scavenging, the charging andsupercharging of the cylinder, instead of the hitherto usual upper rowand lower row of ports, the subsistent third path for the scavengin airbeing totally eliminated, for the purpose of preventing air flowing outtoo soon through the exhaust ports, or short-circuiting.

One example of the object of the inventin is shown diagrammatically inthe accompanying drawing of a single-acting vertical internal combustionengine.

The working cylinder 1 is provided with inlet ports 2 lying opposite theexhaust ports 3, which are closed before the inlet during thecompression stroke by the piston 4, which is shown in the drawing at itslower dead centre. The cylinder is scavenged by air at low pressure,flowing in from the air pipe 5 which can be shut off from the worln'ngspace 7 by means of automatic members-6, whilst, the charging andsupercharging of the working space is effected by air at-a higherpressure taken from the air pipe 8 which is shutoff from theworking'space 7 by the positively controlled members 9. The valve orvalves 9 are controlled by a cam 11 mounted on the shaft 10, the cam 11acting on a lever 12 which in its turn is connected to the valve 9through the rod 13.

According to the invention, common inlet ports v90 2, closed by thepistom during the compression stroke after the exhaust ports, areprovided for scavenging and charging and supercharging. These inletports, through which, under elimina tion ofa third way for thescavenging air, both 05 the air at low pressure used for scavengingv thecylinder and also the air at a higher pressure for charging andsupercharging is led into the cylinder, are directed towards the coverof the working space and are not reached by the piston 4 during thecompression stroke until the piston has moved through a certain distancea of its stroke, for example at least 10%. The passage 16 provided forintroducing the air is formed with a bend in order to control the flowbetter; that is to say, including the bend, etc., the inlet ports aredefined by conduit surfacesrarranged oblique to the cylinder axis andeach of the surfaces being inclined at a different angle to thegeneratrix of the cylinder, as clearly shown in the accompanying drawingat 16, 2. More specifically, the inlet ports are cast or cored in theform of truncated, oblique conesof-revolution,

'with the upper surface slanted downwardly more sure in the workingspace 7 has fallen to or lower than the pressure of the scavenging airin the pipe 5, the valves 6 open; the scavenging of the cylinders beginsand continues until the moment where the piston 4 returning from itslower dead centre position has nearly the position 4* shown in dottedlines, 1. e. shortly before the exhaust ports are covered by the piston.At this moment the valve or valves 9 are fully open (dotted position ofthe piston 4 and of the cam 11) and the charging andsupercharging aircompressed to a higher pressure than the scavenging air flows throughthe ports 2 into the worlnng space '7 until the ports 2 are closed bythe piston during the up-stroke. The charging and supercharging air at ahigher pressure flowing into the passage 15 closes the valves 6. Afterthe piston 5 has closed the ports 2, the valve 9 is led back to its seatwithout shock under the influence of the spring 14.

I claim: v

1. In a two-cycle internal combustion engine, having a cylinderincluding outlet ports, and a single row of inlet ports situatedopposite to the outlet ports for inlet of scavenging, and charging andsupercharging airs, the combination with the said single row of inletports situated opposite to the outlet ports, of automatic members forscavenging the cylinder by air at a low pressure, and positivelycontrolled members for charging and supercharging the cylinder with airat a'higher pressure, the common row of ports for the inlet of thescavenging, and the charging and the supercharging air, being closed bythe piston during the compression stroke after the outlet ports areclosed, for admitting the scavenging and charging and supercharging airto..the cylinder, each of said inletports being defined bysurfacesof-revolution lying oblique to the cylinder axis.

2. In a two-cycle internal combustion engine having a cylinder includingoutlet ports and a single row of inlet ports situated opposite to theoutlet ports for inlet of scavenging, and charging and superchargingairs, the combination with the single row of inlet ports situatedopposite to the outlet ports, of automatic members for scavenging thecylinder by air-at a low pressure, and positively controlled'members forcharging and supercharging the cylinder with air at a higher pressure,the common row of ports for the inlet of the scavenging, and thecharging and the supercharging air, being closed by the piston dur-' ingthe compression stroke after the outlet ports are closed, for admittingthe scavenging and charging and supercharging air to' the cylinder, theinlet ports being bounded by guide surfaces arranged oblique to thecylinder axis, and one part oi the surface of at least one inlet portbeing inclined at a different angle to the generatrix of thecylinder-wall from the rest 0! the surface or said port;

3. In a two-cycle internal combustion engine, having a cylinderincluding outlet ports, and a single row of inlet ports situatedopposite to the outlet ports for inlet of scavenging, and charging andsupercharging airs, the combination with the single row of inlet portssituated opposite to the outlet ports, or automatic members forscavenging the cylinder by air at low pressure, and

' positively controlled members for charging and supercharging-thecylinder with air at a higher pressure, the common row of ports tor theinlet of the scavenging air, and the charging and the supercharging air,being closed by the piston during the compression stroke after theoutlet ports are closed, for admitting the scavenging and charging andsupercharging air to the cylinder.

4. In a two-cycle internal combustion engine having a cylinder includingoutlet ports, and a single row of inlet ports situated opposite to theoutlet ports for inlet of scavenging, and charging and superchargingairs, the combination with the single row of inlet ports situatedopposite to the outlet ports, of automatic members for scavenging thecylinder by air at a low pressure, and

positively controlled members for charging and supercharging thecylinder with air at a higher pressure, the common row of ports for theinlet a or the scavenging air, and the charging andthe superchargingair, being closed by the piston during the compression stroke after theoutlet ports are closed, for admitting the scavenging and charging andsupercharging air to ,the cylinder, 1

the said inlet ports being defined by the revolutionof a generatrixhaving a greater slope toward the vertical at the top or the port thannear the bottom of the port.

5. In a two-cycle internal combustion engine 1 having a cylinderincluding outlet ports, and a single row of inlet ports situatedopposite to the outlet ports for inlet both of scavenging, and ofcharging and supercharging airs in common, the

combination with the said row oi. ports, oi. autol matic members forscavenging the cylinder by air at a low pressure, and positivelycontrolled members for charging and supercharging the cylinder with airat a higher pressure, the row of ports for the common inlet of thescavenging, and o! the 1 cylinder, each of said inlet ports being,bounded 1 by guide surfaces lying oblique to the cylinder axis.

ROBERT momrm.

